• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

MULLARD 3-3

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T

Tubekarus75

Member
Joined 2012
#1
Hello guys! I built the Mullard 3-3 according to the original Mullard schematic.

I have 2 problems:
The R15 resistor (after the EZ81) gets very hot, a 2W type 330Ohm isn't lasting very long. a 5W 330Ohm resistor gets very hot.
Second and frightening problem: The mains transformer is vibrating. This vibrations causes hum to hear coming from the speakers and you can feel the hum!!
Caused by too much current flow? The amp sound great but you can hear the mains transformer humming and vibrating.

I use a transformer kit from primary windings (UK).
I use this mains transformer : https://primarywindings.com/product/mullard-5-10-mono-mains-transformer/
 
#4
A lot of people are dissuaded from building this one because there is a suspicion that you need to have access to good NOS tubes to get the best performance out the circuit - especially the EF86 which is run in 'starvation' mode.

How did it go? What sort of speakers are you using with it?
 
#6
OldHector said:
A lot of people are dissuaded from building this one because there is a suspicion that you need to have access to good NOS tubes to get the best performance out the circuit - especially the EF86 which is run in 'starvation' mode.

How did it go? What sort of speakers are you using with it?
Click to expand...
i tried 2 different pair nos 6p14p from russia, 2 new tad ef86, old valvo & mullard ef86 pulled from vintage gear, some old 7189 pulled from vintage tube receiver without any problems so far.

actually i run 2 nos 6p14p an a pair of ef86 telefunken tubes pulled out of an old tube radio (ef86 with diamond on the bottom)
no problems at all so far.

all "old" tubes have been tested on my sencore tc162 before using in the amp.
 
#10
OldHector said:
A lot of people are dissuaded from building this one because there is a suspicion that you need to have access to good NOS tubes to get the best performance out the circuit - especially the EF86 which is run in 'starvation' mode.

How did it go? What sort of speakers are you using with it?
Click to expand...
Pair of speaker based on ALTEC 614 cabinets design, shown in german Klang&Ton magazine (see enclosed), equipped with Celestion TF1225CX speakers.

See here as well ... https://holgerbarske.com/allgemein/wech-isse/


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